Track dropping of throws clause in Pattern.java.

This is not really an API change because PatternSyntaxException
is unchecked (extends RuntimeException). The behavior has not
changed (PatternSyntaxException can still be thrown).

Bug: 109659282
Test: Treehugger
Change-Id: I5759eee10b27307b68f15fdd6f6f1a258ee01529
1 file changed